The Frequency of Difficult Intubation in Obstetric
Patients: A Report from the Multicenter Perioperative
Outcomes Group Research Consortium
Sharon Chang Reale, MD
Attending Anesthesiologist | Brigham and Women’s Hospital
Instructor in Anesthesia | Harvard Medical School
Background
• Estimates for the incidence of difficult and failed intubation
in the obstetric population vary widely
• Studies largely from countries outside the US or smaller
centers or are dated
Aims
● Estimate the frequency of difficult intubation in obstetrics
● Describe management of difficult intubations
● Determine risk factors for difficult intubation
● Determine if frequency of difficult intubation is higher in
obstetric patients
Methods
● Multicenter, retrospective, observational study
● Women aged 15-44 undergoing general anesthesia for
cesarean delivery at 47 centers
● 2004-2018
Methods
Difficult Intubation
Failed Intubation
Cormack
-Lehane view ≥3
Attempt at intubation
without successful
endotracheal tube
placement
Intubation attempts ≥3
FOI after failed laryngoscopy
SGA followed by successful
intubation
Failed intubation
Methods
● Identified predictors of difficult intubation in cesarean
delivery cohort
● Compared rate of difficult intubation in obstetrics to non-
obstetric surgical patients
○ Age and gender matched
Results
● 14,830 general anesthetics for cesarean delivery
Difficult Intubation
Failed Intubation
N
267 12
% (95% CI)
1.8% (1.6%, 2.0%) 0.08% (0.05%, 0.14%)
Frequency per
general anesthetic
1:55 1:1,235
Difficult Intubation
(n=267)
Cormack
-Lehane view ≥3 245 (96.1%)
Intubation attempts ≥3
38 (16.7%)
FOI followed by successful intubation
4 (1.5%)
SGA followed by successful intubation
25 (9.4%)
Results
Failed Intubation
(n=12)
Rescue supraglottic airway
12 (100%)
Rescue surgical airway
1 (8.3%)
Maternal deaths
0
Results
Univariate Odds Ratio
(95% CIs)
Overall
1:55
BMI
<25
25-39.9
>40
Reference
2.6 (1.3, 5.4)
4.7 (2.2, 10.0)
1:161
1:62
1:35
Mallampati
Score
1or 2
III
IV
Reference
2.0 (1.4, 2.8)
5.6 (3.0, 10.3)
1:70
1:36
1:14
Small hyoid to mentum distance
2.3 (0.8, 6.3) 1:23
Limited jaw protrusion
2.0 (0.6, 6.5) 1:35
Limited mouth opening
7.9 (3.5, 18.0) 1:11
Altered neck anatomy
1.5 (0.7, 3.2) 1:48
Cervical spine limitations
3.9 (1.4, 10.9) 1:14
Induction of labor
2.0 (1.1, 3.7) 1:29
Preeclampsia/Eclampsia
1.3 (0.8, 1.9) 1:45
Results
Total, N
Frequency of difficult
intubation, n (%)
Frequency of failed
intubation, n (%)
Cesarean
deliveries
14,830 267 (1.8%) 12 (0.08%)
Non
-
obstetric
surgery
44,341 356 (0.8%) 0
OR 2.3 (95% CI, 1.9 to 2.7) for CD vs. non-obstetric
Limitations
● Significant variability in documentation
● Limitations to granularity of data
● ICD codes not uniformly present
Conclusions
● Risk of difficult intubation 1:55
● Risk of failed intubation of 1:1,235
● Identifiable risk factors for difficult intubation (BMI, airway
characteristics, induction of labor)
Questions?